Method for preparation of organoalkoxysilanes

Abstract

Disclosed is a one reactor, continuous system for the manufacture of organoalkoxysilanes. The reactor consists of a fractionating means that allows for completion of the reaction and separation of the HCl formed as a by-product. Also disclosed is a means for removing or reducing any residual hydrolyzable chloride or other acids in the organoalkoxysilanes using ion exchange resins.

What is claimed is: 
     
       1. A process for making organoalkoxysilanes using fractionation means consisting essentially of (i) a column comprised of contacting devices (ii) means for providing heat to and partially containing the contents at a sump portion and (iii) means for providing cooling to the contents at a head of the column; wherein the process comprises (A) feeding simultaneously into the column a) an organochlorosilane, (b) liquid alcohol and (c) vaporized alcohol, such that the alcohol contacts the organochlorosilane;   (B) maintaining a temperature within said column such that at least the lower 1/3 of the column is above the boiling point of the alcohol and no reflux of alcohol is present in the head of the column;   (B) recovering any organoalkoxysilane formed from the sump portion of the column; and   (C) recovering HCl at the head of the column.   
     
     
       2. A Process as claimed in claim 1 wherein the alcohol is methanol. 
     
     
       3. A process as claimed in claim 1 wherein the alcohol is ethanol. 
     
     
       4. A process as claimed in claim 1 wherein the organochchlorosilane is 3-methacryloxypropyltrichlorosilane. 
     
     
       5. A process as claimed in claim 4 wherein a reboiler is used as the means to provide heat and the temperature of the reboiler contents is maintained between 70 to 115 degrees Celsius while operating under atmospheric pressure. 
     
     
       6. A process as claimed in claim 4 where the 3-methacryloxypropyltrichlorosilane additionally contains a compound which inhibits polymerization of the acryloxy group. 
     
     
       7. A process as claimed in claim 6 wherein the compound is phenothiazine. 
     
     
       8. A process as claimed in claim 7 wherein the phenolhiazine is present at levels equal to 50 to 500 parts per million parts organochlorosilane. 
     
     
       9. A process as claimed in claim 1 where the organochlorosilane is distilled prior to its introduction into the column. 
     
     
       10. A process as claimed in claim 1 wherein the contacting device comprises trays. 
     
     
       11. A process as claimed in claim 10 wherein the trays are bubble caps. 
     
     
       12. A process as claimed in claim 1 wherein the contacting device comprises packing. 
     
     
       13. A process as claimed in claim 1 wherein the contacting device comprises both packing and trays. 
     
     
       14. A process as claimed in claim 1 wherein the liquid alcohol comprises up to 40 percent of the total alcohol feed with the remainder of the alcohol being vaporized. 
     
     
       15. A process as claimed in claim 1 wherein the vaporized alcohol is fed into the sump portion of the column above said means for providing heat. 
     
     
       16. A process as claimed in claim 1 wherein the liquid alcohol is fed into the head of the column below said means for providing cooling. 
     
     
       17. A process as claimed in claim 16 wherein the liquid alcohol is combined with the organochlorosilane before being fed into the column. 
     
     
       18. A process as claimed in claim 1 wherein an excess of alcohol is continuously supplied. 
     
     
       19. A process as claimed in claim 18 wherein the alcohol is in an excess equal to 101 to 115 percent by weight of the theoretical amount of alcohol necessary for completion of the reaction. 
     
     
       20. A process as claimed in claim 1 wherein the organochlorosilane is hexenylmethyldichlorosilane. 
     
     
       21. A process as claimed in claim 1 wherein the organochlorosilane is methyl-3-methyldichlorosilyl-2-methylpropionate. 
     
     
       22. A method a claimed in claim 1 wherein additionally the organoalkoxysilanes prepared are contacted with an ion exchange resin that is free of hydroxylic materials, to remove any acid. 
     
     
       23. A method as claimed in claim 22 wherein the ion exchange resin is of the anionic type. 
     
     
       24. A method as claimed in claim 22 wherein the ion exchange resin contains reactive tertiary amine groups.